Naturally large cosmological neutrino asymmetries in the minimal supersymmetric standard model

A large neutrino asymmetry could have significant observable consequences for nucleosynthesis and the cosmic microwave background. If the baryon asymmetry originates via the Affleck-Dine mechanism along a d = 4 flat direction of the scalar potential in the minimal supersymmetric standard model and if the lepton asymmetry originates via Affleck-Dine leptogenesis along a d = 6 direction, corresponding to the lowest dimension directions conserving R parity, then the ratio n(L)/n(B) is naturally in the range 10(8)-10(9). As a result, a potentially observable neutrino asymmetry is correlated with a baryon asymmetry of the order of 10(-10).     

Proposal for a supersymmetric standard model

The fact that neutrinos are massive suggests that the minimal supersymmetric standard model (MSSM) might be extended in order to include three gauge-singlet neutrino superfields with Yukawa couplings of the type H2Lnuc. We propose to use these superfields to solve the mu problem of the MSSM without having to introduce an extra singlet superfield as in the case of the next-to-MSSM (NMSSM). In particular, terms of the type nuc H1H2 in the superpotential may carry out this task spontaneously through neutrino vacuum expectation values. In addition, terms of the type (nuc)3 avoid the presence of axions and generate effective Majorana masses for neutrinos at the electroweak scale. On the other hand, these terms break lepton number and R parity explicitly. For Dirac masses of the neutrinos of order 10(-4) GeV, eigenvalues reproducing the correct scale of neutrino masses are obtained.     

No-scale supersymmetric standard model

We propose a class of supergravity models coupled to matter in which the scales of supersymmetry breaking and of weak gauge symmetry breaking are both fixed by dimensional transmutation, not put in by hand. The models have a flat potential with zero cosmological constant before the evaluation of weak radiative corrections which determine $\text{m}\text{3}\text{2}\text{, m}{}_{\mathrm{<mtext>W</mtext>}}\text{=}\text{exp}\text{[}\text{?O(1)}\text{α}{}_{\mathrm{<mtext>t</mtext>}}\text{]m}{}_{\mathrm{<mtext>p</mtext>}}\text{:α}{}_{\mathrm{<mtext>t</mtext>}}\text{= O(α)}$. These models are consistent with all particle physi cs and cosmological constraints for top quark masses in the range 30 GeV < m_t < 100 GeV.     

Constrained next-to-minimal supersymmetric standard model

We consider the fully constrained version of the next-to-minimal supersymmetric extension of the standard model (cNMSSM) in which a singlet Higgs superfield is added to the two doublets that are present in the minimal extension (MSSM). Assuming universal boundary conditions at a high scale for the soft supersymmetry-breaking mass parameters as well as for the trilinear interactions, we find that the model is more constrained than the celebrated minimal supergravity model. The phenomenologically viable region in the parameter space of the cNMSSM corresponds to a small value for the universal scalar mass m_{0}: in this case, one single input parameter is sufficient to describe the model's phenomenology once constraints from collider data and cosmology are imposed.     

Gauge-invariant inflaton in the minimal supersymmetric standard model

We argue that all the necessary ingredients for successful inflation are present in the flat directions of the Minimally Supersymmetric Standard Model. We show that out of many gauge-invariant combinations of squarks, sleptons, and Higgs bosons, there are two directions, LLe and udd, which are promising candidates for the inflaton. The model predicts more than 10(3) e-foldings, with an inflationary scale of H(inf) approximately O(1-10) GeV, provides a tilted spectrum with an amplitude of delta(H) approximately 10(-5) and a negligible tensor perturbation. The temperature of the thermalized plasma could be as low as T(rh) approximately O(1-10) TeV. Parts of the inflaton potential can be determined independently of cosmology by future particle physics experiments.     

LEP Higgs boson searches beyond the standard model and minimum supersymmetric standard model

Ever since the center-of-mass energy was increased in 1995 above the Zℴ resonance, the four LEP experiments (ALEPH, DELPHI, OPAL and L3) have renewed their effort to search for the Higgs boson. Data taking ended in the year 2000 with about 130 pb⁻¹ of data collected per experiment above 206 GeV ine ⁺ e ⁻¹ collisions but the data analysis is still very active. Most recently, the wealth of theoretical models and predictions has stimulated new analyses and model interpretations which go beyond the standard model and minimal supersymmetric standard model. These include the searches for charged Higgs bosons, models with two Higgs field doublets, searches for ‘fermiophobic’ Higgs decay, invisible Higgs boson decays, decay-mode independent searches, and limits on Yukawa and anomalous Higgs couplings. I review the searches done by the four LEP experiments and present the LEP combined results when they exist.     

Nonlinear supersymmetric standard model and its phenomenology

We consider the Higgs sector of a nonlinear supersymmetric standard model. Analytic solutions for some useful mass relations are derived. We investigate physical consequences of the model for LEP 1, LEP 2, and 500, 1000 resp. 2000 GeV LCs, and show that the neutral scalar Higgs bosons will most probably enable LC 500, 1000, 2000 to test the model conclusively, whereas at LEP 1, 2 only a part of the parameter space can be explored. As for the two pseudoscalar Higgs bosons the lighter one cannot be detected at any of the considered colliders, whereas the heavier one could possibly be detected with about “10 percent probability” at LC 1000 and LC 2000.     

On the supersymmetric sine-Gordon model

The basic model in a new trend in supersymmetry and soliton theory is presented. Exact soliton-like solutions of the supercovariant coupled equations of motion are obtained. From this a bag model is constructed.Talk given at the ldSymposium on Mathematical Methods in the Theory of Elementary Particles, Liblice castle, Czechoslovakia, June 18–23, 1978.     

Electric dipole moments in the generic supersymmetric standard model

The generic supersymmetric standard model is a model built from a supersymmetrized standard model field spectrum and the gauge symmetries only. The popular minimal supersymmetric standard model differs from the generic version in having R parity imposed by hand. We review an efficient formulation of the model and some of the recently obtained interesting phenomenological features, focusing on one-loop contributions to fermion electric dipole moments.